diff --git a/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py b/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py
index 2bdecdfe47..419590bc59 100644
--- a/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py
+++ b/src/clusterfuzz/_internal/bot/tasks/utasks/fuzz_task.py
@@ -1169,6 +1169,11 @@ def create_testcase(group: uworker_msg_pb2.FuzzTaskCrashGroup,
   comment = (f'Fuzzer {fully_qualified_fuzzer_name} generated testcase crashed '
              f'in {crash.crash_time} seconds '
              f'(r{fuzz_task_output.crash_revision})')
+
+  fuzzer = uworker_io.entity_from_protobuf(uworker_input.setup_input.fuzzer,
+                                           data_types.Fuzzer)
+  is_trusted = fuzzer.trusted
+
   testcase_id = data_handler.store_testcase(
       crash=crash,
       fuzzed_keys=crash.fuzzed_key or None,
@@ -1192,9 +1197,7 @@ def create_testcase(group: uworker_msg_pb2.FuzzTaskCrashGroup,
       timeout_multiplier=get_testcase_timeout_multiplier(
           group.context.timeout_multiplier, crash, group.context.test_timeout),
       minimized_arguments=crash.arguments,
-      # TODO(https://github.com/google/clusterfuzz/issues/4175): Before enabling
-      # oss-fuzz-on-demand change this.
-      trusted=True)
+      trusted=is_trusted)
   testcase = data_handler.get_testcase_by_id(testcase_id)
   events.emit(
       events.TestcaseCreationEvent(
diff --git a/src/clusterfuzz/_internal/tests/core/bot/tasks/utasks/fuzz_task_test.py b/src/clusterfuzz/_internal/tests/core/bot/tasks/utasks/fuzz_task_test.py
index cbe1d2419c..f67a2113d9 100644
--- a/src/clusterfuzz/_internal/tests/core/bot/tasks/utasks/fuzz_task_test.py
+++ b/src/clusterfuzz/_internal/tests/core/bot/tasks/utasks/fuzz_task_test.py
@@ -38,7 +38,6 @@
 from clusterfuzz._internal.bot.tasks.utasks import uworker_io
 from clusterfuzz._internal.bot.untrusted_runner import file_host
 from clusterfuzz._internal.build_management import build_manager
-from clusterfuzz._internal.datastore import data_handler
 from clusterfuzz._internal.datastore import data_types
 from clusterfuzz._internal.fuzzing import corpus_manager
 from clusterfuzz._internal.google_cloud_utils import big_query
@@ -2092,25 +2091,69 @@ def setUp(self):
         one_time_crasher_flag=False,
     )
     self.uworker_input = _create_uworker_input()
+    fuzzer = data_types.Fuzzer(name='engine', trusted=True)
+    fuzzer.put()
+    self.uworker_input.setup_input.fuzzer.CopyFrom(
+        uworker_io.entity_to_protobuf(fuzzer))
     self.uworker_output = uworker_msg_pb2.Output(
         fuzz_task_output=uworker_msg_pb2.FuzzTaskOutput(crash_revision='1'))
 
   def test_create_testcase_event_emit(self):
     """Test that the create_testcase method emits the expected event."""
     self.mock.store_testcase.side_effect = _store_generic_testcase
-    fuzz_task.create_testcase(
+    testcase = fuzz_task.create_testcase(
         group=self.group,
         uworker_input=self.uworker_input,
         uworker_output=self.uworker_output,
         fully_qualified_fuzzer_name='engine')
-
-    testcase = data_handler.get_testcase_by_id(1)
     self.mock.emit.assert_called_once_with(
         events.TestcaseCreationEvent(
             testcase=testcase,
             creation_origin=events.TestcaseOrigin.FUZZ_TASK,
             uploader=None))
 
+  def test_create_testcase_trusted_fuzzer(self):
+    """Test creating a testcase with a trusted fuzzer."""
+    fuzzer = data_types.Fuzzer(name='engine', trusted=True)
+    fuzzer.put()
+
+    self.uworker_input.setup_input.CopyFrom(uworker_msg_pb2.SetupInput())
+    self.uworker_input.setup_input.fuzzer.CopyFrom(
+        uworker_io.entity_to_protobuf(fuzzer))
+
+    self.mock.store_testcase.side_effect = _store_generic_testcase
+
+    fuzz_task.create_testcase(
+        group=self.group,
+        uworker_input=self.uworker_input,
+        uworker_output=self.uworker_output,
+        fully_qualified_fuzzer_name='engine')
+
+    self.mock.store_testcase.assert_called_once()
+    kwargs = self.mock.store_testcase.call_args[1]
+    self.assertTrue(kwargs.get('trusted'))
+
+  def test_create_testcase_untrusted_fuzzer(self):
+    """Test creating a testcase with an untrusted fuzzer."""
+    fuzzer = data_types.Fuzzer(name='engine', trusted=False)
+    fuzzer.put()
+
+    self.uworker_input.setup_input.CopyFrom(uworker_msg_pb2.SetupInput())
+    self.uworker_input.setup_input.fuzzer.CopyFrom(
+        uworker_io.entity_to_protobuf(fuzzer))
+
+    self.mock.store_testcase.side_effect = _store_generic_testcase
+
+    fuzz_task.create_testcase(
+        group=self.group,
+        uworker_input=self.uworker_input,
+        uworker_output=self.uworker_output,
+        fully_qualified_fuzzer_name='engine')
+
+    self.mock.store_testcase.assert_called_once()
+    kwargs = self.mock.store_testcase.call_args[1]
+    self.assertFalse(kwargs.get('trusted'))
+
 
 def _store_generic_testcase(*args, **kwargs):  # pylint: disable=unused-argument
   """Store a generic testcase and return its id."""